Electric switch



Patented De'c. 9, 1930 UNITED STATES PATENT OFFICE VICTOR R. DESPARD, CF VALPARAI80,-INDIANA, ASSIGNOR T MCGILL MANUFACTUR- ING COMPANY, 0F VALPARAISO, INDIANA, A CORPORATION 0F INDIANA ELECTRIC SWITCH Application filed June 8, 1927. Serial No. 196,259.

M invention relates to electric switches and lxas for its primary object the provision of a device of this character which is capable of standing up under severe usage and heavy surges of current without danger of freezing the contacts together or wearing them away rapidly. Since the nitrogen filled lamps have come` into general use, considerable diiiiculty has been encountered in the use of switches for this type of light since the nitrogen lamp when starting cold has much less resistance than it does after heating up. The excessive rush of current upon closing the switch to such a lamp sometimes results in the switch contacts which are not fully brought together being heated by the arc across the gap between them so that they run to ether or freeze, and this, of course, renders t e switch inoperative.

In a nitrogen lamp with five hundred watts, for instance, starting cold, there is a rush of forty-five amps. for a period of about a half of a second. On the three hundred watt lamp when it is first started, it takes about twenty-four amps. for one-tenth of a second. While it is possible, of course, to

utilize heavier contacts and get a greater contactin surface in the switches, this is objectionabe because of the added force necessary to o erate the switch. Since switches, particu arly of the type shown by applicant in this case, are operated byx the strength of a spring, an increase in t e strength of the spring would necessarily make for an increase in the amount of pull to operate the switch and this would result in too great a strain being placed upon the mounting.

To avoid this difficulty, I provide at one of the stationary contacts a pair of spring fingers which are ieldable away from each other and in additlon provide upon the movable bridging member a second pair of yielding contacts or spring fingers so that immediately upon the contacts passing out of engagement, the spring action causes them to swing transversely to the direction of the movable contact and break the arc that would follow. Again in going into contact, the two pairs of yielding spring contacts give a good wiping effect so that a good direct metal other advantage in addition to the wiping to metal contact is made as the movable contacts snap into engagement with the station ar'` one. l

he use of these spring contacts gives an- 5' contact made when they engage by causing o the arcv to be broken in openin the switch immediately when the two sets o spring contacts are disengaged. This advanta e is particularly useful in lamps of the car on type wherein the current increases as the lamp heats up so that in breaking the circuit a greater current is cut off than is established 1n making the circuit.

Other ob'ects and advantages of the in-f vention will appear as the description proceeds in connection with the accompanying drawings. However, it is obvious that various changes may be made in the exact structural details without de arting from the spirit of the invention and) I intend to avail myself of all such changes as fall within the sco e of the claims.

n the drawings:

Fig. 1 is a side view showing the movable contacts in an intermediate position;

Fi 2 is a horizontalsection taken the line 2-2 of Fig. 1; and

Fig. 3 is a vertical section on the line 3--3 o'f F1 1.

Re erring now in detail to the drawings, the switch mechanism is mounted upon a pair of insulating plates 5 and 6 which are connected by means of the metal side pieces 7 and 8 having projecting lugs extending through the insulatin plates as shown at 9 and 10 and upset to orm a rigid structure. The plates 7 and 8 are provided with the terminals 11 and 12 for connection to a source of current.

The stationary contacts consist of the fiat plate members 13 and 14 which as shown in Figs. 1 and 2, have apertures therethrough .receiving the lugs 9 and 10 upon the members 7 and 8 whereby they are secured rigidly in place when these lugs are upset against the insulating disk 5. The members 13 and 14 are then turned up as indicated at 15 and 16 and the long spring arms 17 and 18 extend substantially parallel to the plate 5 100 along to form fingers for the stationary contacts. These spring fingers 17 and 18 as shown clearly in F ig. 1 are curved transversely as at 19 and 20 so that the movable contacts 21 and 22 similarly curved will engage them as the contacts move together and press them outwardly to obtain a good wiping contact under the yielding pressurenof the spring arms 17 and 18 and the spring portions 23 and 24 of the movable contact fingers 21 and 22. These contact fingers 21 and 22 as shown in Fig. 2 are secured to the U-shaped bridging member 25 by means of the integral clip portions 26 and 27 and by welding or soldering in any suitable manner.

This U-shaped bridging member is pivoted at 28 to the insulating pivot members 29 and 30 and is connected to the operating spring 31 by means of the insulating piece 32 at its forward end. This spring is connected at its opposite end to the operating mechanism in a manner similar to that shown in the application of David D. Gordon, Serial No. 467,965, filed May 9, 1921, on an electric switch. The U-shaped member 25 is caused to snap back and forth from the position engaging the contacts 17 and 18 with the spring ngers 21 and 22 to the position shown in Fig. 3 in a manner similar to that shown in the above named application. This part-icular switch movement itself forms no part of this invention and therefore will not be further described.

From the above description it will be seen that as the movable bridging member moves the spring fingers 21 and 22 into engagement with the contacts 17 and 18 at their rounded portions 19 and 20, considerable force is eX- erted to bring the contacts into tight engagement due to the spring arms upon the contacts and thus a good wiping contact is made immediately. Again 1n moving out of Contact the spring fingers 21 and 22 the moment they pass out of engagement with the portions 19 and 20 are thrown outwardl by the spring arms and this carries the arc w ich would ordinarily follow the spring arms outwardly and causes it to break much more quickly than it does in the ordinary straight movement. The spring fingers 21 and 22 are preferably made so that they are about half as strong in the spring action as the spring arms 17 and 18 so that in breaking the contact they will have a wider throw and thus aid in breaking the arc more quickly.

Having thus described my invention, what I desire to claim and secure by Letters Patent of the United States is:

1. An electric switch comprising a support, spaced spring contacts mounted on said support and yieldable toward and away from each other, abridging member, and means for snappin said bridging member into and out of position connecting said spring contacts, said bridging member having spring fingers for engaging said contacts.

2. An electric switch comprising a sup ort, spaced spring contacts mounted thereon, avin their contact faces oppositely directed, a brldging member, means for moving said bridging member transversely to the direction in which said contacts face into and out of position connecting said contacts, and cooperating means on said contacts and member for throwing the arc caused by disconnecting said member and contacts outwardly at an angle to the direction of movement of said member, said means including spring fingers on said member adapted to engage said contacts and having the advancing edges thereof curved away from said contacts, Said spaced contacts having convex contacting faces.

In witness whereof, hereunto subscribe 

